What is a Data Type?

What-is-Data-Type

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In computer science, data types or just type is a classification that differentiates data into a real-valued, integer, or Boolean.

Almost all programming languages explicitly include the notion of data type, though different languages may use different terminology. Common data types may include integers, booleans, characters, floating-point numbers, and alphanumeric strings.

What is a Data Type?

A data type, in programming, is a classification that specifies which type of value a variable has and what type of mathematical, relational, or logical operations can be applied to it without causing an error.

A data type is an attribute associated with a piece of data that tells a computer system how to interpret its value.

A string, for example, is a data type that is used to classify text and an integer is a data type used to classify whole numbers.

Data TypeUsed ForExample
StringAlphanumeric charactersHello World
IntegerIntegers453, -3987
Floating PointNumbers with decimal point654.786
CharacterTextA, x , i
BooleanLogical valuesTRUE, FALSE

Understanding data types ensures that data is collected in the preferred format and the value of each property is as expected.

What is a Data Type

Remember that data types are not to be confused with the two types of data together referred to as customer data  — entity data and event data.

A good understanding of data types is required to properly define event properties and entity properties. A well-defined tracking plan must contain the data type of every property to ensure data accuracy and prevent data loss.

Before jumping into the importance of data types, let’s take a look at some of the common data types.

Common Data Types

  • Integer (int): It is the most common numeric data type used to store numbers without a fractional component (-707, 0, 707).
  • Floating Point Numbers (float): It is also a numeric data type used to store numbers that may have a fractional component like monetary values do (707.07, 0.7, 707.00). Remember that number is often used as a data type that includes both int and float types.
  • Character (char): It is used to store a single letter, digit, punctuation mark, symbol, or blank space. 
  • String: It is a sequence of characters and the most commonly used data type to store text. Additionally, a string can also include digits and symbols, however, it is always treated as text. A phone number is usually stored as a string (+1-999-666-3333) but can also be stored as an integer (9996663333).
  • Boolean: It represents the values true and false. When working with the boolean data type, it is helpful to keep in mind that sometimes a boolean value is also represented as 0 (for false) and 1 (for true). 
  • Enumerated type (enum): It contains a small set of predefined unique values (also known as elements or enumerators) that can be compared and assigned to a variable of enumerated data type. The values of an enumerated type can be text-based or numerical. In fact, the boolean data type is a pre-defined enumeration of the values true and false. For example, if rock and jazz are the enumerators, an enumerated type variable genre can be assigned either of the two values, but not both. Assuming that you are asked to fill in your preferences on a music app and are asked to choose either one of the two genres via a dropdown menu, the variable genre will store either rock or jazz. With enumerated type, values can be stored and retrieved as numeric indices (0, 1, 2) or strings. 
  • Array: Also known as a list, an array is a data type that stores a number of them in a specific order, typically all of the same types. Since an array stores multiple elements or values, the structure of data stored by an array is referred to as an array data structure. Each element of an array can be retrieved using an integer index (0, 1, 2,…), and the total number of elements in an array represents the length of an array. For example, an array variable genre can store one or more of the elements rock, jazz, and blues. The indices of the three values are 0 (rock), 1 (jazz), and 2 (blues), and the length of the array is 3  (since it contains three elements). Continuing on the example of the music app, if you are asked to choose one or more of the three genres and you happen to like all three (cheers to that), the variable genre will store all three elements (rock, jazz, blues). 
  • Date: Needs no explanation; typically stores date in the YYYY-MM-DD format (ISO 8601 syntax). 
  • Time: Stores a time in the hh:mm:ss format. Besides the time of the day, it can also be used to store the time elapsed or the time interval between two events which could be more than 24 hours. For example, the time elapsed since an event took place could be 72+ hours (72:00:59).  
  • Datetime: Stores a value containing both date and time together in the YYYY-MM-DD hh:mm:ss format. 
  • Timestamp: Typically represented in Unix time, a timestamp represents the number of seconds that have elapsed since midnight (00:00:00 UTC), 1st January 1970. It is typically used by computer systems to log the precise date and time of an event, down to the number of seconds, in a format that is unaffected by time zones. Therefore unlike datetime, the timestamp remains the same irrespective of your geographical location.

Types of Data Type

In a broad sense, there are three types of data types −

  • Fundamental data types − These are the predefined data types that are used by the programmer directly to store only one value as per requirement, i.e., integer type, character type, or floating type. For example − int, char, float, etc.
  • Derived data types − These data types are derived using built-in data types which are designed by the programmer to store multiple values of the same type as per their requirement. For example − Array, Pointer, function, list, etc.
  • User-defined data types − These data types are derived using built-in data types which are wrapped into a single data type to store multiple values of either the same type or a different type or both as per the requirement. For example − Class, Structure, etc.

Data Types Supported by C++

The following table lists the data types supported by C++

Data TypeSizeRange
char1 byte-128 to 127 or 0 to 255
unsigned char1 byte0 to 255
signed char1 byte-128 to 127
int4 bytes-2147483648 to 2147483647
unsigned int4 bytes0 to 4294967295
signed int4 bytes-2147483648 to 2147483647
short int2 bytes-32768 to 32767
unsigned short int2 bytes0 to 65,535
signed short int2 bytes-32768 to 32767
long int4 bytes-2,147,483,648 to 2,147,483,647
signed long int4 bytes-2,147,483,648 to 2,147,483,647
unsigned long int4 bytes0 to 4,294,967,295
float4 bytes+/- 3.4e +/- 38 (~7 digits)
double8 bytes+/- 1.7e +/- 308 (~15 digits)
long double8 bytes+/- 1.7e +/- 308 (~15 digits)

Data Types Supported by Java

The following data types are supported by Java −

Data TypeSizeRange
byte1 byte-128 to 127
char2 byte0 to 65,536
short2 byte-32,7688 to 32,767
int4 byte-2,147,483,648 to 2,147,483,647
long8 byte-9,223,372,036,854,775,808 to 9,223,372,036,854,775,807
float4 byte-2147483648 to 2147483647
double8 byte+9.223*1018
Boolean1 bitTrue or False

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